Tensioning mechanisms and methods for articulating surgical instruments such as for use in robotic surgical systems

Abstract

An articulation assembly for a robotic surgical instrument includes a plurality of rotatable but longitudinally fixed lead screws extending between first and second base plates, a collar threaded about each lead screws and configured to translate therealong in response to rotation of the corresponding lead screw, an articulation cable coupled to each collar and defining or having a threaded shaft, and a threaded nipple threaded about each of the threaded shafts. Each threaded nipple is engaged with one of the collars to thereby engage each of the articulation cables with a corresponding one of the collars such that longitudinal translation of the corresponding collar pushes or pulls the corresponding articulation cable. Each threaded nipple is configured for further threading or unthreading about the corresponding threaded shaft to vary a pre-tension on the corresponding articulation cable.

What is claimed is: 
     
       1. An articulation assembly for a robotic surgical instrument, comprising:
 first and second base plates; 
 a plurality of lead screws extending between the first and second base plates, each lead screw rotatable but longitudinally fixed relative to the first and second base plates; 
 a collar disposed in threaded engagement about each of the lead screws, each collar configured to translate longitudinally along a corresponding one of the lead screws in response to rotation of the corresponding lead screw; 
 an articulation cable coupled to each of the collars, each articulation cable defining or having engaged therewith a threaded shaft; and 
 a threaded nipple disposed in threaded engagement about each of the threaded shafts, each threaded nipple engaged with one of the collars to thereby engage each of the articulation cables with a corresponding one of the collars such that longitudinal translation of the corresponding collar pushes or pulls the corresponding articulation cable, 
 wherein each threaded nipple is configured for further threading or unthreading about the corresponding threaded shaft to vary a pre-tension on the corresponding articulation cable, and 
 wherein each collar defines a ferrule configured for receipt of the corresponding threaded nipple in engagement therewith. 
 
     
     
       2. The articulation assembly according to  claim 1 , wherein the plurality of lead screws includes four lead screws arranged in a generally square cross-sectional configuration. 
     
     
       3. The articulation assembly according to  claim 1 , further comprising at least one guide dowel extending between the first and second base plates and coupled with at least one of the collars to inhibit rotation of the at least one collar. 
     
     
       4. The articulation assembly according to  claim 3 , wherein each collar includes at least one C-shaped channel, the at least one C-shaped channel of each collar configured to receive a portion of the at least one guide dowel therein to inhibit rotation of each collar. 
     
     
       5. The articulation assembly according to  claim 1 , further comprising a plurality of proximal gear assemblies configured to drive rotation of the plurality of lead screws. 
     
     
       6. The articulation assembly according to  claim 5 , wherein a coupling gear couples two of the proximal gear assemblies such that two of the lead screws are driven by a single input, the coupling gear locking the pre-tension on the articulation cables corresponding to the two lead screws. 
     
     
       7. A robotic surgical instrument, comprising:
 a housing; 
 a shaft extending distally from the housing, the shaft longitudinally secured to the housing thereby maintaining the shaft in fixed longitudinal position relative to the housing; 
 a fixed plate disposed within the housing, the fixed plate longitudinally secured to the housing thereby maintaining the fixed plate in fixed longitudinal position relative to the shaft and the housing; 
 an actuation assembly disposed within the housing, a portion of the actuation assembly including:
 first and second base plates; 
 a plurality of lead screws extending distally from the first base plate to the second base plate, each lead screw rotatable but longitudinally fixed relative to the first and second base plates; 
 a collar disposed in threaded engagement about each of the lead screws, each collar configured to translate longitudinally along a corresponding one of the lead screws in response to rotation of the corresponding lead screw; and 
 an articulation cable coupled to each of the collars such that translation of one of the collars tensions or un-tensions a corresponding one of the articulation cables; and 
 
 at least one biasing member disposed between the second base plate and the fixed plate to bias the portion of the actuation assembly proximally relative to the housing and the shaft, thereby biasing the articulation cables proximally to apply a pre-tension thereto. 
 
     
     
       8. The robotic surgical instrument according to  claim 7 , wherein the plurality of lead screws includes four lead screws arranged in a generally square cross-sectional configuration. 
     
     
       9. The robotic surgical instrument according to  claim 7 , further comprising at least one guide dowel extending between the first and second base plates and coupled with at least one of the collars to inhibit rotation of the at least one collar. 
     
     
       10. The robotic surgical instrument according to  claim 9 , wherein each collar includes at least one C-shaped channel, the at least one C-shaped channel of each collar configured to receive a portion of the at least one guide dowel therein to inhibit rotation of each collar. 
     
     
       11. The robotic surgical instrument according to  claim 7 , wherein the at least one biasing member is disposed about the shaft. 
     
     
       12. The robotic surgical instrument according to  claim 7 , wherein the at least one biasing member is centered relative to the plurality of lead screws to substantially equally pre-tension the articulation cables. 
     
     
       13. The robotic surgical instrument according to  claim 7 , wherein the at least one biasing member is a coil compression spring. 
     
     
       14. An articulation assembly for a robotic surgical instrument, comprising:
 first and second base plates; 
 a plurality of lead screws extending distally from the first base plate to the second base plate, each lead screw rotatable but longitudinally fixed relative to the first and second base plates; 
 a collar disposed in threaded engagement about each of the lead screws, each collar configured to translate longitudinally along a corresponding one of the lead screws in response to rotation of the corresponding lead screw; 
 an articulation cable coupled to each of the collars such that translation of one of the collars tensions or un-tensions a corresponding one of the articulation cables; and 
 a biasing member disposed coaxially about each of the lead screws between the corresponding collar and the second base plate, each biasing member configured to bias the corresponding collar proximally relative to the second base plate, thereby biasing the articulation cables proximally to apply a pre-tension thereto. 
 
     
     
       15. The articulation assembly according to  claim 14 , wherein the plurality of lead screws includes four lead screws arranged in a generally square cross-sectional configuration. 
     
     
       16. The articulation assembly according to  claim 14 , further comprising at least one guide dowel extending between the first and second base plates and coupled with at least one of the collars to inhibit rotation of the at least one collar. 
     
     
       17. The articulation assembly according to  claim 16 , wherein each collar includes at least one C-shaped channel, the at least one C-shaped channel of each collar configured to receive a portion of the at least one guide dowel therein to inhibit rotation of each collar. 
     
     
       18. The articulation assembly according to  claim 14 , wherein the biasing members are similar to one another such that the articulation cables are substantially equally pre-tensioned. 
     
     
       19. The articulation assembly according to  claim 14 , wherein the biasing members are coil compression springs.